Which sort of cemented my belief that the people who want to stay young forever are, principally, aging researchers, and prompted this. I'm not sure if it doesn't need more fleshing out (and if that would just require more words).
No one knew whether it was a boon or a curse to aging research; all they knew was if you wanted to get into that field, you were a hundred years too late. There just weren’t any job openings, and because of the serum no one was dying – or getting any older – any time soon. In fact, aging research was one of the few fields fundamentally changed by the serum. So while some biologists stayed young forever and athletes stayed twenty-five until they died in tragic accidents, the rest of us lived as humans have always lived: short, bright lives.The other thing it made me think of, because I am a huge nerd, is a future in which humans are, basically, Time Lords: time travel + regenerative medicine. You can live forever, just not necessarily in your same body.